Large areas of the Southwest United States where evaporative cooling is either the sole, or primary method of cooling, for many residential or commercial buildings are effected by annual, and significant changes in the normally dry air. These changes are created by summer storms originating in Mexico and moving into the Southwestern United States, generally by late June. Commonly referred to as the "Monsoon Season" these storm conditions last from late June to early September and account for the majority of the annual rainfall in large parts of the Southwest; as well as accounting for a significant increase in humidity during those months, over the preceeding, and subsequent months, when evaporative cooling is used. The high humidity, combined with high temperatures, during the "Monsoon Season" markedly decreases the ability of evaporative coolers to provide room cooling, even with full-time usage. One way to alleviate the problem is to provide a means to reduce the external moisture content of air drawn into the evaporative coolers; thereby enhancing the evaporative cooling process.
A 3,400 CFM side-draft evaporative cooler will have three pads, each one having an area of approximately 28 inches by 28 inches. A cooler this size is designed, generally, for buildings under 1,300 square feet; larger buildings will require correspondingly larger coolers and pads. Generally, these coolers are mounted on roofs, for both the residential and commercial buildings. Because of their placement, and the direct exposure of the evaporative cooler pads to the atmosphere, evaporative coolers are prime locations for the deposit of airborne pollens, molds, and dirt. With the propensity of residents to introduce non-indigenous plants to metropolitan areas of the Southwest has come the associated problem of allergies. The pollen problem, in Tucson, Ariz. has risen to the point where Tucson now ranks among the top ten American cities in pollen count, according to the local NBC television affiliate; a paradoxical situation since many people have moved there from other parts of the country because of respiratory problems. One method to alleviate the problem of airborne pollen, mold, and dirt entering buildings equipped with evaporative coolers is to modify the coolers in such a manner as to reduce the amount of exposure the cooler pads receive directly from the atmosphere, and the prevailing winds.
During the late spring and early summers in the Southwest, specifically in Arizona, when evaporative cooling is in use, a drought-like weather condition exists. At these times birds seeking water will land on the pad frame louvers in order to drink water percolating down the louvers and pads and subsequently leaving feces and feathers in and on the evaporative coolers. There exists then a potential for the transmission of disease from the birds' feces to the interior of a room, with the evaporative cooler serving as the medium. The reservoir of water in the evaporative coolers is also treated in many cases with chemical additives designed to kill algae and dissolve mineral deposits. Birds drinking the percolating water from coolers treated with these additives also risk contamination of themselves and their eggs through ingestion. One option to remove the possibility of contamination to humans and birds is to modify the coolers in such a way as to deny birds access to the water passing over and through the pads and louvers, respectively.